We intend to explore further the effects of local potassium infusion into regions of myocardium, using fluoroscopically placed cardiac catheters in the coronary arteries. This technique simulates ischemia and usually induces serious ventricular arrhythymias. As antiarrhythmic drugs (lidocaine, procainamide, practolol) will allow survival of about 70%, we will continue infusion to evaluate the effects on regional myocardial function and blood flow. Studies this past year showed that continued K ion infusion induced a regional blood flow decline, and we are currently utilizing radioactive microspheres to determine the layer flow in the perfused region. We also intend to evaluate the degree to which antiarrhythmic agents penetrate the injured area. To do this we will use labeled 14C procainamide as an antiarrhythmic and measure the drug concentration in the K ion perfused and non-K ion perfused regions. We also hope to evaluate the use of slow reductions in K ion infusion rate to determine myocardial function and composition late following such infusions.